Error code 27 questions!
 

Okay guys...
I have an 89 FC S5 Vert.
ECU is going into limp mode, and throwing the code 27.
If i shut off the car, turn it back on, its gone for 2 mins then comes back on while driving.
I have searched this forum for a while, and no help.... all i found was one guy who replaced the OMP...
do i have any other options?

Nope. Series 5 ECU's must, repeat, MUST see the OMP there and functioning, otherwise it will go into limp mode. You only have four options:

1) replace the OMP
2) block -off the OMP, and the oil injecors but leave it connected (electrically speaking) and hanging somehwere in the engine bay and pre-mix
3) get an Rtek and remove it.... and pre-mix
4) go full stand-alone EMS and remove it.... and pre-mix

And geez there must be hundreds of threads about this.....

Right on, but option 2 would still require a replacement OMP. The ECU would need to see a functional one.

Reading your local FSM helps.

It's got all sorts of ideas as to what to do if you get one of those codes.

Replaced OMP -
No difference.....
This sucks.

with a NEW one or one that someone was selling cause it was bad?

also you should check the harness they do fail too

+1

Verify that the OMP is fucntioning, the Harness isn't FUBAR'd and also, make sure that the ECU is not fried. It is quite common in s5's for the electric OMP to fail, and take the ECU out with it. Like I said before above, kill it. kill it, kill it, kill it. pre-mix.

I think I am ready to kill it. Since this is an S5 - all the research i have done on the site tells me I will have to leave the OMP in there to fool the ecu....
the problem I have - is there is a problem somewhere causing the ecu to throw a 27 (OMP) failure code. so even if i do this, and keep the OMP in there connected (buried in the engine compartment somewhere), this problem will not go away - Or am I wrong?

also, call me a noob, but I have done some searching, and can't find a good writeup on premixing in a 13b.... someone point me to a good thread please?

Dear Sir-

We regret to inform you that your ECU, having choked on the MOP, has met an untimely death. :(

Sincerely,

Da Club.

https://www.rx7club.com/2nd-generation-specific-1986-1992-17/s5-mop-ecu-failure-diagnosis-710938/

I have one fs. Pm me
Thanks Robert

sometimes when the OMP fails it'll take some of the ECU with it... either you got a second bad OMP or your ECU is now bad to. It's also quite possible that your ECU being bad fried your new OMP if that's the case...


premixing: 1 ounce of TCW-3 2-stroke oil per gallon of gasoline you put in. Put the 2-stroke in before the gas, so the gas going in mixes it up.

I have decided to go the premix route, since I am no longer going to drive this car as my daily driver. I am going to build this bad boy, and go back to driving my toaster.
I need to locate a block off plate for the OMP, and I guess I will have to replace the ECU now to determine if both OMPs I have are defective...

check the harness first, they do go bad and it ends up grounding the ecu thru the MOP which fries both

http://www.2751engineering.com/
http://www.banzai-racing.com/
http://www.pineappleracing.com/

all those places sell block-off plates.

I would just get another ECU and put a rtek chip in it, they can delete the need for an OMP from the ECU.

http://www.pocketlogger.com/index.php?pid=rtek7